Molecular Markers Mapped around the High Shoot Regeneration Capacity Gene Rg-2 in Lycopersicon chilense.

Abstract

From one BC1F1-44-15 plant(Takashina et al. 1998), which has a high capacity to regenerate shoots from root explants of L.chilense PI128644 and is self-compatible, we obtained the BC1F2 plants. They were analyzed for their capacity to regenerate adventitious shoots from root explants in vitro. The BC1F2 plants showed a bimodal distribution with two groups based on their shoot regeneration rates. Plants with a high shoot regeneration capacity and low shoot regeneration capacity segregated at a 3/1 ratio. This suggests that the shoot regeneration capacity derived from L.chilense PI128644 is controlled by a major dominant gene, which was designated as Rg-2. About 60 random amplified polymorphic DNA (RAPD) bands specific to the wild species used as a parent were generated in the BC1F1-44-15 plant using 140 ranom primers. Ten of the 60 RAPD markers, were linked to the gene for high shoot regeneration capacity by a modified bulked segregant analysis using BC2F1 plants. The segregation of 12 markers(an RFLP marker TG102 mapped on chromosome 3, a marker of the acid invertase gene invchi and 10 RAPD markers) was examined by using a BC1F2 generation. A linkage map of the molecular markers was constructed around the gene Rg-2 for the high shoot regeneration capacity. The gene Rg-2 was located at 3.2 cM from a cluster including seven RAPD markers, as well as the gene invchi.